and Applied Mechanics
56, 4, pp. 1083-1095, Warsaw 2018
DOI: 10.15632/jtam-pl.56.4.1083
Numerical loss analysis in a compressor cascade with leading edge tubercles
edge tubercles in a high speed compressor cascade. Taking the lead from flippers of the
humpback whale, tubercles are passive structures of a blade for flow control. Evaluation
of the overall performance in terms of entropy increase shows that the loss reduction is
achieved both at high negative and high positive incidence angles, while a rise in the loss is
obtained near the design point. And a smaller wave number as well as a smaller amplitude
results in lower additional losses at the design point. Spanwise and streamwise distributions
of pitchwise-averaged entropy increase combined with flow details have been presented to
survey the loss development and, subsequently, to interpret the loss mechanism. The tubercle
geometry results in the deflection flow and the consequent spanwise pressure gradient. This
pressure gradient induces formation of counter-rotating streamwise vortices, transports away
the low-momentum fluid near wall from crests towards troughs and leads to local high loss
regions behind troughs as well as loss reduction behind the crests in comparison to the
baseline. The interaction between these vortices and flow separation by momentum transfer
leads to separation delay and the consequent loss reduction at the outlet.
References
Denton J.D., 1993, Loss mechanisms in turbomachines, Journal of Turbomachinery, 115, 4, 621-656
Dorfner C., Hergt A., Nicke E., Moenig R., 2011, Advanced nonaxisymmetric endwall
contouring for axial compressors by generating an aerodynamic separator-part i: principal cascade
design and compressor application, Journal of Turbomachinery, 133, 2, 021026
Fischer A., Riess W., Seume J.R., 2003, Performance of strongly bowed stators in a 4-stage
high speed compressor, ASME Proceedings, GT2003-38392, 429-435
Fish F.E., Battle J.M., 1995, Hydrodynamic design of the humpback whale flipper, Journal of
Morphology, 225, 1, 51-60
Fish F.E., Lauder G.V., 2006, Passive and active flow control by swimming fishes and mammals,
Annual Review of Fluid Mechanics, 38, 193-224
Hansen K.L., Kelso R.M., Dally B.B., 2011, Performance variations of leading-edge tubercles
for distinct airfoil profiles, AIAA Journal, 49, 1, 185-194
Hergt A., Meyer R., Engel K., 2013, Effects of vortex generator application on the performance
of a compressor cascade, Journal of Turbomachinery, 135, 2, 021026
Johari H., Henoch C., Custodio D., Levshin A., 2007, Effects of leading-edge protuberances
on airfoil performance, AIAA Journal, 45, 11, 2634-2642
Keerthi M. C., Kushari A., De A., Kumar A., 2014, Experimental investigation of effects of
leading-edge tubercles on compressor cascade performance, ASME Proceedings, GT2014-26242
Lord W.K., Macmartin D.G., Tillman T. G., 2000, Flow control opportunities in gas turbine
engines, Proceedings of AIAA, AIAA 2000-2234
Miklosovic D.S., Murray M.M., Howle L.E., Fish F.E., 2004, Leading-edge tubercles delay
stall on humpback whale (Megaptera novaeangliae) flippers, Physics of Fluids, 16, 5, L39-L42
Pedro H.T.C., Kobayashi M.H., 2008, Numerical study of stall delay on humpback whale
flippers, Proceedings of AIAA, AIAA 2008-0584
Steinert W., Eisenberg B., Starken H., 1991, Design and testing of a controlled diffusion
airfoil cascade for industrial axial flow compressor application, Journal of Turbomachinery, 113, 4, 583-590